29 August 2005 Automated fringe-pattern extrapolation for patterned surface profiling by interference microscopy with Fourier transform analysis
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Abstract
Fringe pattern demodulation by the Fourier transform method associated with fringe extrapolation by the Gerchberg algorithm was investigated in details for its application to fast profiling of surfaces with small patterns and/or cuttings. For such surfaces, spectral leakage is a major concern as it corrupts data in a large part of the areas of interest if extrapolation is not carried out. Simulated fringe patterns or real interferograms recorded on micromechanical devices by interference microscopy were used for this evaluation. Different filter shapes in the Fourier space were tested for the determination of valid areas in the interferogram, for the fringe extrapolation stage and for the final phase demodulation. It is demonstrated that filters with a shape adapted to the modulation sidelobe in the Fourier space allow automated measurements without user expertise while maintaining a high accuracy. Some practical rules for the choice of extrapolation margins, fringe density, fringe extrapolation iteration number and other parameters are clarified to reach accurate and fast automated measurements.
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Cedric Breluzeau, Alain Bosseboeuf, Sylvain Petitgrand, Xavier Leroux, "Automated fringe-pattern extrapolation for patterned surface profiling by interference microscopy with Fourier transform analysis", Proc. SPIE 5858, Nano- and Micro-Metrology, 58580B (29 August 2005); doi: 10.1117/12.612270; https://doi.org/10.1117/12.612270
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